3? Analyfis and Expcrimints with Sulphate of Sirontlati-, JjCf. 



in the weight of the precipitate, and that of the 162,5 grains taken up by the marine acid, 

 arofe from decanting the folution into different veflels. 



4. To detecSl any finall portion of barites which might be contained in the precipitate, a 

 quantity of marine acid was poured on it, fufficient to diffolve only a few grains of the earth. 

 Had anv barites been prefent, it would hjive been taken up in preference to the ftrontian, 

 from its fuperior affinity for the acid ; the folution, however, after digeflion for fcveral hours, 

 flili cryflallized in needles, and afforded a copious precipitate to baritic lime-water. 



5. 164 grains of the precipitated carbonate of ftrontian were thrown into marine acid, 

 which extricated, as before, about 47 grains of carbonic acid, leaving nearly one grain undif- 

 folved : the addition of fulphuric acid to the folution reproduced 200,8 grains of fulphate of 

 ftrontian. 



ft The folution of pot-afh. No. i, was then taken, and the whole of the carbonic acid re- 

 maining in it difengaged by .an excefs of marine acid : the addition of muriate of barites 

 afforded a precipitate, which, after drying in a red heat, weighed nearly 249 grains : had the 

 whole of the 200 grains been decompofed, the folution would have furnifhed nearly 250 grains 

 of fulphate of barites. 



Klaproth and Dr. Withering having eftimated the quantity of fulphuric acid contained in 

 artificial fulphate at 33, and Fourcroy at 35, of the fpecific gravity of 2,24, or that contained in 

 fulphate of pot-afh ; before the concentration of the acid contained in fulphate of ftrontian 

 could be known, it was necefTary to make the following experiments : 



7. 218,5 grains of artificial fulphate of barites were decompofed by digefting with a folu- 

 tion of carbonate of pot-afh, producing 190 grains of carbonate of barites, from which 

 marine acid feparated 42 grains of carbonic acid, leaving nearly 14 grains of earth in folution : 

 from this experiment it appears that fulphate of barites contains about 32,2 per cent of acid. 



To find the concentration of this acid, 124 grains of fulphuric acid of 1,843 Specific gravity, 

 containing (according to Kirwan's table, in the Irifh Tranfa£lions) 109,12 grains of ftandard, 

 or 97,42 grains of 2,24, were precipitated by baritic lime-water, producing 283,3 grains of 

 fulphate of barites, containing nearly 34,4 per cent of acid of 2,24 fpecific gravity. 



9. 92,2 grains of the fame acid were precipitated by a folution of muriate of barites, the 

 fulphate of barites weighed nearly 212 grains, containing about 34,1 percent of acid of 2,24. 

 By taking the mean of thefe experiments, we may eftimate the quantity of acid contained in 

 fulphate of barites at 33 per cent of the fpecific gravity of 2,24. 



According to this calculation, the 250 grains of fulphate of barites, No. 6, would furnifh 

 82,5 grains of acid of the above ftrength; 



10. To afcertain the difference between native and artificial fulphate of ftrontian, 204,2 grains 

 of fulphuric acid of 1,843 (containing 160,44 grains of 2,24 fpecific gravity) were precipitated 

 by ftrontian lime-water, producing 360 grains of fulphate of ftrontian, containing about 44,5 

 per cent of acid. This accounts for the 200,8 of fulphate being produced from 163 grains 

 of carbonate of ftrontian. No. 5. Hence the proportion of acid in the artificial will exceed that 

 of the native nearly 2 per cent. 



11. To determine whether the folution. No. 2, contained any calcareous earth, a fmall 

 quantity of oxalic acid was added to it i no precipitation, however, took place. 



12. Pruf£ate 



